/*
Copyright (C) 1996-1997 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/
// Z_zone.c

#include "quakedef.h"

#define	DYNAMIC_SIZE	0xc000

#define	ZONEID	0x1d4a11
#define MINFRAGMENT	64

typedef struct memblock_s
{
    int		size;           // including the header and possibly tiny fragments
    int     tag;            // a tag of 0 is a free block
    int     id;        		// should be ZONEID
    struct memblock_s       *next, *prev;
    int		pad;			// pad to 64 bit boundary
} memblock_t;

typedef struct
{
    int		size;		// total bytes malloced, including header
    memblock_t	blocklist;		// start / end cap for linked list
    memblock_t	*rover;
} memzone_t;

void Cache_FreeLow (int new_low_hunk);
void Cache_FreeHigh (int new_high_hunk);


/*
==============================================================================

						ZONE MEMORY ALLOCATION

There is never any space between memblocks, and there will never be two
contiguous free memblocks.

The rover can be left pointing at a non-empty block

The zone calls are pretty much only used for small strings and structures,
all big things are allocated on the hunk.
==============================================================================
*/

memzone_t	*mainzone;

void Z_ClearZone (memzone_t *zone, int size);


/*
========================
Z_ClearZone
========================
*/
void Z_ClearZone (memzone_t *zone, int size)
{
    memblock_t	*block;

// set the entire zone to one free block

    zone->blocklist.next = zone->blocklist.prev = block =
                               (memblock_t *)( (byte *)zone + sizeof(memzone_t) );
    zone->blocklist.tag = 1;	// in use block
    zone->blocklist.id = 0;
    zone->blocklist.size = 0;
    zone->rover = block;

    block->prev = block->next = &zone->blocklist;
    block->tag = 0;			// free block
    block->id = ZONEID;
    block->size = size - sizeof(memzone_t);
}


/*
========================
Z_Free
========================
*/
void Z_Free (void *ptr)
{
    memblock_t	*block, *other;

    if (!ptr)
        Sys_Error ("Z_Free: NULL pointer");

    block = (memblock_t *) ( (byte *)ptr - sizeof(memblock_t));
    if (block->id != ZONEID)
        Sys_Error ("Z_Free: freed a pointer without ZONEID");
    if (block->tag == 0)
        Sys_Error ("Z_Free: freed a freed pointer");

    block->tag = 0;		// mark as free

    other = block->prev;
    if (!other->tag)
    {
        // merge with previous free block
        other->size += block->size;
        other->next = block->next;
        other->next->prev = other;
        if (block == mainzone->rover)
            mainzone->rover = other;
        block = other;
    }

    other = block->next;
    if (!other->tag)
    {
        // merge the next free block onto the end
        block->size += other->size;
        block->next = other->next;
        block->next->prev = block;
        if (other == mainzone->rover)
            mainzone->rover = block;
    }
}


/*
========================
Z_Malloc
========================
*/
void *Z_Malloc (int size)
{
    void	*buf;

    Z_CheckHeap ();	// DEBUG
    buf = Z_TagMalloc (size, 1);
    if (!buf)
        Sys_Error ("Z_Malloc: failed on allocation of %i bytes",size);
    Q_memset (buf, 0, size);

    return buf;
}

void *Z_TagMalloc (int size, int tag)
{
    int		extra;
    memblock_t	*start, *rover, *new, *base;

    if (!tag)
        Sys_Error ("Z_TagMalloc: tried to use a 0 tag");

//
// scan through the block list looking for the first free block
// of sufficient size
//
    size += sizeof(memblock_t);	// account for size of block header
    size += 4;					// space for memory trash tester
    size = (size + 7) & ~7;		// align to 8-byte boundary

    base = rover = mainzone->rover;
    start = base->prev;

    do
    {
        if (rover == start)	// scaned all the way around the list
            return NULL;
        if (rover->tag)
            base = rover = rover->next;
        else
            rover = rover->next;
    }
    while (base->tag || base->size < size);

//
// found a block big enough
//
    extra = base->size - size;
    if (extra >  MINFRAGMENT)
    {
        // there will be a free fragment after the allocated block
        new = (memblock_t *) ((byte *)base + size );
        new->size = extra;
        new->tag = 0;			// free block
        new->prev = base;
        new->id = ZONEID;
        new->next = base->next;
        new->next->prev = new;
        base->next = new;
        base->size = size;
    }

    base->tag = tag;				// no longer a free block

    mainzone->rover = base->next;	// next allocation will start looking here

    base->id = ZONEID;

// marker for memory trash testing
    *(int *)((byte *)base + base->size - 4) = ZONEID;

    return (void *) ((byte *)base + sizeof(memblock_t));
}


/*
========================
Z_Print
========================
*/
void Z_Print (memzone_t *zone)
{
    memblock_t	*block;

    Con_Printf ("zone size: %i  location: %p\n",mainzone->size,mainzone);

    for (block = zone->blocklist.next ; ; block = block->next)
    {
        Con_Printf ("block:%p    size:%7i    tag:%3i\n",
                    block, block->size, block->tag);

        if (block->next == &zone->blocklist)
            break;			// all blocks have been hit
        if ( (byte *)block + block->size != (byte *)block->next)
            Con_Printf ("ERROR: block size does not touch the next block\n");
        if ( block->next->prev != block)
            Con_Printf ("ERROR: next block doesn't have proper back link\n");
        if (!block->tag && !block->next->tag)
            Con_Printf ("ERROR: two consecutive free blocks\n");
    }
}


/*
========================
Z_CheckHeap
========================
*/
void Z_CheckHeap (void)
{
    memblock_t	*block;

    for (block = mainzone->blocklist.next ; ; block = block->next)
    {
        if (block->next == &mainzone->blocklist)
            break;			// all blocks have been hit
        if ( (byte *)block + block->size != (byte *)block->next)
            Sys_Error ("Z_CheckHeap: block size does not touch the next block\n");
        if ( block->next->prev != block)
            Sys_Error ("Z_CheckHeap: next block doesn't have proper back link\n");
        if (!block->tag && !block->next->tag)
            Sys_Error ("Z_CheckHeap: two consecutive free blocks\n");
    }
}

//============================================================================

#define	HUNK_SENTINAL	0x1df001ed

typedef struct
{
    int		sentinal;
    int		size;		// including sizeof(hunk_t), -1 = not allocated
    char	name[8];
} hunk_t;

byte	*hunk_base;
int		hunk_size;

int		hunk_low_used;
int		hunk_high_used;

qboolean	hunk_tempactive;
int		hunk_tempmark;

void R_FreeTextures (void);

/*
==============
Hunk_Check

Run consistancy and sentinal trahing checks
==============
*/
void Hunk_Check (void)
{
    hunk_t	*h;

    for (h = (hunk_t *)hunk_base ; (byte *)h != hunk_base + hunk_low_used ; )
    {
        if (h->sentinal != HUNK_SENTINAL)
            Sys_Error ("Hunk_Check: trahsed sentinal");
        if (h->size < 16 || h->size + (byte *)h - hunk_base > hunk_size)
            Sys_Error ("Hunk_Check: bad size");
        h = (hunk_t *)((byte *)h+h->size);
    }
}

/*
==============
Hunk_Print

If "all" is specified, every single allocation is printed.
Otherwise, allocations with the same name will be totaled up before printing.
==============
*/
void Hunk_Print (qboolean all)
{
    hunk_t	*h, *next, *endlow, *starthigh, *endhigh;
    int		count, sum;
    int		totalblocks;
    char	name[9];

    name[8] = 0;
    count = 0;
    sum = 0;
    totalblocks = 0;

    h = (hunk_t *)hunk_base;
    endlow = (hunk_t *)(hunk_base + hunk_low_used);
    starthigh = (hunk_t *)(hunk_base + hunk_size - hunk_high_used);
    endhigh = (hunk_t *)(hunk_base + hunk_size);

    Con_Printf ("          :%8i total hunk size\n", hunk_size);
    Con_Printf ("-------------------------\n");

    while (1)
    {
        //
        // skip to the high hunk if done with low hunk
        //
        if ( h == endlow )
        {
            Con_Printf ("-------------------------\n");
            Con_Printf ("          :%8i REMAINING\n", hunk_size - hunk_low_used - hunk_high_used);
            Con_Printf ("-------------------------\n");
            h = starthigh;
        }

        //
        // if totally done, break
        //
        if ( h == endhigh )
            break;

        //
        // run consistancy checks
        //
        if (h->sentinal != HUNK_SENTINAL)
            Sys_Error ("Hunk_Check: trahsed sentinal");
        if (h->size < 16 || h->size + (byte *)h - hunk_base > hunk_size)
            Sys_Error ("Hunk_Check: bad size");

        next = (hunk_t *)((byte *)h+h->size);
        count++;
        totalblocks++;
        sum += h->size;

        //
        // print the single block
        //
        memcpy (name, h->name, 8);
        if (all)
            Con_Printf ("%8p :%8i %8s\n",h, h->size, name);

        //
        // print the total
        //
        if (next == endlow || next == endhigh || strncmp (h->name, next->name, 8) )
        {
            if (!all)
                Con_Printf ("          :%8i %8s (TOTAL)\n",sum, name);
            count = 0;
            sum = 0;
        }

        h = next;
    }

    Con_Printf ("-------------------------\n");
    Con_Printf ("%8i total blocks\n", totalblocks);

}

/*
===================
Hunk_AllocName
===================
*/
void *Hunk_AllocName (int size, char *name)
{
    hunk_t	*h;

#ifdef PARANOID
    Hunk_Check ();
#endif

    if (size < 0)
        Sys_Error ("Hunk_Alloc: bad size: %i", size);

    size = sizeof(hunk_t) + ((size+15)&~15);

    if (hunk_size - hunk_low_used - hunk_high_used < size)
        Sys_Error ("Hunk_Alloc: failed on %i bytes",size);

    h = (hunk_t *)(hunk_base + hunk_low_used);
    hunk_low_used += size;

    Cache_FreeLow (hunk_low_used);

    memset (h, 0, size);

    h->size = size;
    h->sentinal = HUNK_SENTINAL;
    Q_strncpy (h->name, name, 8);

    return (void *)(h+1);
}

/*
===================
Hunk_Alloc
===================
*/
void *Hunk_Alloc (int size)
{
    return Hunk_AllocName (size, "unknown");
}

int	Hunk_LowMark (void)
{
    return hunk_low_used;
}

void Hunk_FreeToLowMark (int mark)
{
    if (mark < 0 || mark > hunk_low_used)
        Sys_Error ("Hunk_FreeToLowMark: bad mark %i", mark);
    memset (hunk_base + mark, 0, hunk_low_used - mark);
    hunk_low_used = mark;
}

int	Hunk_HighMark (void)
{
    if (hunk_tempactive)
    {
        hunk_tempactive = false;
        Hunk_FreeToHighMark (hunk_tempmark);
    }

    return hunk_high_used;
}

void Hunk_FreeToHighMark (int mark)
{
    if (hunk_tempactive)
    {
        hunk_tempactive = false;
        Hunk_FreeToHighMark (hunk_tempmark);
    }
    if (mark < 0 || mark > hunk_high_used)
        Sys_Error ("Hunk_FreeToHighMark: bad mark %i", mark);
    memset (hunk_base + hunk_size - hunk_high_used, 0, hunk_high_used - mark);
    hunk_high_used = mark;
}


/*
===================
Hunk_HighAllocName
===================
*/
void *Hunk_HighAllocName (int size, char *name)
{
    hunk_t	*h;

    if (size < 0)
        Sys_Error ("Hunk_HighAllocName: bad size: %i", size);

    if (hunk_tempactive)
    {
        Hunk_FreeToHighMark (hunk_tempmark);
        hunk_tempactive = false;
    }

#ifdef PARANOID
    Hunk_Check ();
#endif

    size = sizeof(hunk_t) + ((size+15)&~15);

    if (hunk_size - hunk_low_used - hunk_high_used < size)
    {
        Con_Printf ("Hunk_HighAlloc: failed on %i bytes\n",size);
        return NULL;
    }

    hunk_high_used += size;
    Cache_FreeHigh (hunk_high_used);

    h = (hunk_t *)(hunk_base + hunk_size - hunk_high_used);

    memset (h, 0, size);
    h->size = size;
    h->sentinal = HUNK_SENTINAL;
    Q_strncpy (h->name, name, 8);

    return (void *)(h+1);
}


/*
=================
Hunk_TempAlloc

Return space from the top of the hunk
=================
*/
void *Hunk_TempAlloc (int size)
{
    void	*buf;

    size = (size+15)&~15;

    if (hunk_tempactive)
    {
        Hunk_FreeToHighMark (hunk_tempmark);
        hunk_tempactive = false;
    }

    hunk_tempmark = Hunk_HighMark ();

    buf = Hunk_HighAllocName (size, "temp");

    hunk_tempactive = true;

    return buf;
}

/*
===============================================================================

CACHE MEMORY

===============================================================================
*/

typedef struct cache_system_s
{
    int						size;		// including this header
    cache_user_t			*user;
    char					name[16];
    struct cache_system_s	*prev, *next;
    struct cache_system_s	*lru_prev, *lru_next;	// for LRU flushing
} cache_system_t;

cache_system_t *Cache_TryAlloc (int size, qboolean nobottom);

cache_system_t	cache_head;

/*
===========
Cache_Move
===========
*/
void Cache_Move ( cache_system_t *c)
{
    cache_system_t		*new;

// we are clearing up space at the bottom, so only allocate it late
    new = Cache_TryAlloc (c->size, true);
    if (new)
    {
//		Con_Printf ("cache_move ok\n");

        Q_memcpy ( new+1, c+1, c->size - sizeof(cache_system_t) );
        new->user = c->user;
        Q_memcpy (new->name, c->name, sizeof(new->name));
        Cache_Free (c->user);
        new->user->data = (void *)(new+1);
    }
    else
    {
//		Con_Printf ("cache_move failed\n");

        Cache_Free (c->user);		// tough luck...
    }
}

/*
============
Cache_FreeLow

Throw things out until the hunk can be expanded to the given point
============
*/
void Cache_FreeLow (int new_low_hunk)
{
    cache_system_t	*c;

    while (1)
    {
        c = cache_head.next;
        if (c == &cache_head)
            return;		// nothing in cache at all
        if ((byte *)c >= hunk_base + new_low_hunk)
            return;		// there is space to grow the hunk
        Cache_Move ( c );	// reclaim the space
    }
}

/*
============
Cache_FreeHigh

Throw things out until the hunk can be expanded to the given point
============
*/
void Cache_FreeHigh (int new_high_hunk)
{
    cache_system_t	*c, *prev;

    prev = NULL;
    while (1)
    {
        c = cache_head.prev;
        if (c == &cache_head)
            return;		// nothing in cache at all
        if ( (byte *)c + c->size <= hunk_base + hunk_size - new_high_hunk)
            return;		// there is space to grow the hunk
        if (c == prev)
            Cache_Free (c->user);	// didn't move out of the way
        else
        {
            Cache_Move (c);	// try to move it
            prev = c;
        }
    }
}

void Cache_UnlinkLRU (cache_system_t *cs)
{
    if (!cs->lru_next || !cs->lru_prev)
        Sys_Error ("Cache_UnlinkLRU: NULL link");

    cs->lru_next->lru_prev = cs->lru_prev;
    cs->lru_prev->lru_next = cs->lru_next;

    cs->lru_prev = cs->lru_next = NULL;
}

void Cache_MakeLRU (cache_system_t *cs)
{
    if (cs->lru_next || cs->lru_prev)
        Sys_Error ("Cache_MakeLRU: active link");

    cache_head.lru_next->lru_prev = cs;
    cs->lru_next = cache_head.lru_next;
    cs->lru_prev = &cache_head;
    cache_head.lru_next = cs;
}

/*
============
Cache_TryAlloc

Looks for a free block of memory between the high and low hunk marks
Size should already include the header and padding
============
*/
cache_system_t *Cache_TryAlloc (int size, qboolean nobottom)
{
    cache_system_t	*cs, *new;

// is the cache completely empty?

    if (!nobottom && cache_head.prev == &cache_head)
    {
        if (hunk_size - hunk_high_used - hunk_low_used < size)
            Sys_Error ("Cache_TryAlloc: %i is greater then free hunk", size);

        new = (cache_system_t *) (hunk_base + hunk_low_used);
        memset (new, 0, sizeof(*new));
        new->size = size;

        cache_head.prev = cache_head.next = new;
        new->prev = new->next = &cache_head;

        Cache_MakeLRU (new);
        return new;
    }

// search from the bottom up for space

    new = (cache_system_t *) (hunk_base + hunk_low_used);
    cs = cache_head.next;

    do
    {
        if (!nobottom || cs != cache_head.next)
        {
            if ( (byte *)cs - (byte *)new >= size)
            {
                // found space
                memset (new, 0, sizeof(*new));
                new->size = size;

                new->next = cs;
                new->prev = cs->prev;
                cs->prev->next = new;
                cs->prev = new;

                Cache_MakeLRU (new);

                return new;
            }
        }

        // continue looking
        new = (cache_system_t *)((byte *)cs + cs->size);
        cs = cs->next;

    }
    while (cs != &cache_head);

// try to allocate one at the very end
    if ( hunk_base + hunk_size - hunk_high_used - (byte *)new >= size)
    {
        memset (new, 0, sizeof(*new));
        new->size = size;

        new->next = &cache_head;
        new->prev = cache_head.prev;
        cache_head.prev->next = new;
        cache_head.prev = new;

        Cache_MakeLRU (new);

        return new;
    }

    return NULL;		// couldn't allocate
}

/*
============
Cache_Flush

Throw everything out, so new data will be demand cached
============
*/
void Cache_Flush (void)
{
    while (cache_head.next != &cache_head)
        Cache_Free ( cache_head.next->user );	// reclaim the space
}

/*
============
Cache_Print

============
*/
void Cache_Print (void)
{
    cache_system_t	*cd;

    for (cd = cache_head.next ; cd != &cache_head ; cd = cd->next)
    {
        Con_Printf ("%8i : %s\n", cd->size, cd->name);
    }
}

/*
============
Cache_Report

============
*/
void Cache_Report (void)
{
    Con_Printf ("%4.1f megabyte data cache\n", (hunk_size - hunk_high_used - hunk_low_used) / (float)(1024*1024) );
}

/*
============
Cache_Init

============
*/
void Cache_Init (void)
{
    cache_head.next = cache_head.prev = &cache_head;
    cache_head.lru_next = cache_head.lru_prev = &cache_head;

    Cmd_AddCommand ("flush", Cache_Flush);
    Cmd_AddCommand ("cache_report", Cache_Report);
}

/*
==============
Cache_Free

Frees the memory and removes it from the LRU list
==============
*/
void Cache_Free (cache_user_t *c)
{
    cache_system_t	*cs;

    if (!c->data)
        Sys_Error ("Cache_Free: not allocated");

    cs = ((cache_system_t *)c->data) - 1;

    cs->prev->next = cs->next;
    cs->next->prev = cs->prev;
    cs->next = cs->prev = NULL;

    c->data = NULL;

    Cache_UnlinkLRU (cs);
}



/*
==============
Cache_Check
==============
*/
void *Cache_Check (cache_user_t *c)
{
    cache_system_t	*cs;

    if (!c->data)
        return NULL;

    cs = ((cache_system_t *)c->data) - 1;

// move to head of LRU
    Cache_UnlinkLRU (cs);
    Cache_MakeLRU (cs);

    return c->data;
}


/*
==============
Cache_Alloc
==============
*/
void *Cache_Alloc (cache_user_t *c, int size, char *name)
{
    cache_system_t	*cs;

    if (c->data)
        Sys_Error ("Cache_Alloc: allready allocated");

    if (size <= 0)
        Sys_Error ("Cache_Alloc: size %i", size);

    size = (size + sizeof(cache_system_t) + 15) & ~15;

// find memory for it
    while (1)
    {
        cs = Cache_TryAlloc (size, false);
        if (cs)
        {
            strncpy (cs->name, name, sizeof(cs->name)-1);
            c->data = (void *)(cs+1);
            cs->user = c;
            break;
        }

        // free the least recently used cahedat
        if (cache_head.lru_prev == &cache_head)
            Sys_Error ("Cache_Alloc: out of memory");
        // not enough memory at all
        Cache_Free ( cache_head.lru_prev->user );
    }

    return Cache_Check (c);
}

//============================================================================


/*
========================
Memory_Init
========================
*/
void Memory_Init (void *buf, int size)
{
    int p;
    int zonesize = DYNAMIC_SIZE;

    hunk_base = buf;
    hunk_size = size;
    hunk_low_used = 0;
    hunk_high_used = 0;

    Cache_Init ();
    p = COM_CheckParm ("-zone");
    if (p)
    {
        if (p < com_argc-1)
            zonesize = Q_atoi (com_argv[p+1]) * 1024;
        else
            Sys_Error ("Memory_Init: you must specify a size in KB after -zone");
    }
    mainzone = Hunk_AllocName (zonesize, "zone" );
    Z_ClearZone (mainzone, zonesize);
}

